Labor and delivery: Intermittent auscultation or electronic fetal monitors?

Evidence is mixed on whether electronic fetal monitors truly prevent more stillbirths and reduce neonatal morbidity and mortality compared with intermittent auscultation.

One of the hallmarks of midwifery is no intervention in the absence of complications. I try to keep this in mind while caring for pregnant women, particularly on the labor and delivery floor at the hospital where intervention is the norm. 

The most common and accepted intervention in modern hospital labor rooms is the electronic fetal monitor (EFM). Continuous fetal monitoring traces the fetal heart rate pattern externally using ultrasound and is usually accompanied by a second monitor that traces uterine contractions. 

Initially introduced in the late 1960s, the goal of EFM was to recognize fetal hypoxia earlier in order to prevent stillbirth and reduce neonatal morbidity and mortality.  The idea was to continuously observe how the fetus was tolerating labor. By the early 1980s, continuous EFM had widely replaced the practice of intermittent auscultation (IA) of fetal heart tones during labor.

A 2007 Cochrane review of 12 trials comparing IA and EFM demonstrated no significant differences in neonatal mortality or cerebral palsy, and only a modest reduction in neonatal seizures with EFM. Continuous EFM was associated with an increase in cesarean sections and instrumental vaginal delivery. 

Almost every woman who presents to the labor and delivery unit at a hospital immediately gets hooked up to EFM. Nurses, midwives and physicians evaluate the “strip” that is produced and make clinical decisions based on that strip. A questionable fetal heart rate pattern can lead to more interventions, such as artificial rupture of membranes, labor augmentation with pitocin, internal monitoring and emergency cesarean section.

As a provider, it is difficult not to react to a poor strip or even to a questionable one.  For every poor outcome, there are malpractice attorneys waiting to question the provider's decisions related to that EFM strip. It is no wonder that the rise of EFM use correlates with a rise in cesarean deliveries. 

Personally I'd like to see a movement back toward IA in low-risk labors, a choice backed by both the American College of Nurse Midwives and the American College of Obstetricians and Gynecologists. However, the main barrier to this practice is the availability of nursing care, as it requires almost 1:1 care during active labor.

Interestingly, a new study by Chen et al was just published in the June 2011 issue of the American Journal of Obstetrics and Gynecology.  The researchers analyzed EFM in 1,732,211 live births and found that the practice was associated with a significant decrease in neonatal morbidity and mortality. Though this study was not a comparison of EFM with IA, it will be interesting to see what impact this has on guidelines for fetal surveillance in the future.

Which do you use in your practice, IA or EFM, and why? Share your opinion in the comments box below.

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